Carbon clamp



March 30, 1948. c. E. GRAHAM CARBON CLAMP Filed July 29, 1946 2 Sheets-Sheet 1 Carl E. Graham W aflomcgs March 30, 1943- c. E. GRAHAM 2,438,

CARBON CLAMP Filed July 29, 1946 2 Shets-Sheec 2 IN VEN TOR.

5 I garlEl z ralzam $1M wagfl A TTORNEYS Patented Mar. 30, 1948 UNITED YRATENT lemma EARBON CLAMP Gar-lE.:Graham,-antcn,i:0hio

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1 The invention-relates to carbon clamps *and more particularly to a clampespeciallydeslgned 'for holding the carbon-in-t-he lamp -house-' for the usual type of auction-- picture projectors, -and the present invention is -a continuationin part of my co-pending applicationSerial-No. 587513 2,

filed April 7, 1945, abandoned August 21,19 415.

In the-type of lamp housewhich is commonly used in conection 'WibhIIiOlliOIl'PiQblllG projectors, due to the construction of the lamphouse 'and projector, thefeedscrew which-feeds thepos'itive carbon toward "the arc "is limite'jcPto -ten inches in length,;and sincethecarbons which are provided for thispurpose are fourteen inches in length, it is not possibletoclamp-ag-new full length carbon at its extreme end when-thesame is first placedin the lamp-house.

This requires clamping the carbona'boutifour inches from the end untila sufiicientamount of the carbon has been'burned away to "permit-bit" to be clamped at its end. It frequently-happens that this initial clamping of the carbon at a point spaced from its end cracks'iorjfractures the carbon at this point and sinces these carbons are covered With a copper coatingthe -ately removed and replacedandthismayhapPen while a film is being ,runthrough theprojector causing considerable annoyance and difficulty.

,In this common type of lamphouse-th'e post which is operatively connected to thefeedjscrew and carries the carbon clamp is inclinedjfiorwardly at substantially a 45 angle to the vertical, anda relatively short head-for-the'oarbpn clamp is pivotally connected to-theiupperiend of this post, the main lead wire'beinggconnected to the rear end'of the carbon clamp.

This requires that the forward end 'of thefhead be provided with a weight to counterbalance the weight of the lead wire so as toho'ld the forward end portion of the positive carbon downiim'the usual V-shape guide ordinarily- -provided for that purpose.

My invention contemplates animprovementyin such lamp houses which comprisesa vertical'gpost mounted upon the positive feed screw' 'an'd; an elongated head which is pivotally -mounted-at (Chi-1M1!!!) -post--anii carries the carbon clamp wherby' the 'forwardl-y extending elongated head 'i's df suzmcieritweighttocounter balance the lead wire and holdthecarbon-"down in the v-shape i=5 The object of thepresent-invention"isfiiofprow ill overcome the objections and --'dilficultife's --whi=ch willclamp-the-end *o'f anew carbon it is first installed in the lamp houseean d which 'anad-j-ustment-is Y provided the clamp itself to compensate -for -th'edifference in lehgiihibkatwe'en the new-carbon land the--usual ieed screw A -fur'ther obi elitis -41o provi cle 'a carbon clampin device of-this haracter which may be alttached -to -the --p ositive post of the -lamp 'housing jreplac'ing the I "conventional carbon clamp. A st-ill further object is the provision carbon-wclamp "comprising ---an elongated ii *for attachment tothe positive post and-pr0vided "with-a guideway and acarbon clamping. member afdius'tably -mounted -in ithe guileway 1 (if saiiii head.

-Anoth'er object-"of the -i nv-er'iticni's to provide a -carbon--cl-amp including an elengated head having a depending ear near one end arfd a *counterwei'ght iormed "upon I the adiacent end It-is st-ill manner -eb'ject to provide a carbon f "d-evice comprising an elongated head o 1- corresponding to the *difierence I in lengt'h he tween the feed screw and-thecarb'en,

-- A -further object of theinvention is to crevice v40 --a device o'f -t'hje charatiter referre'd--to including-hr vertical posit eperati-vely mounted upon saii d screw,- an -elongated head pivotal-1y oonnectefd at its rear end --to the -vertic'a'l "post and a carbon "clamp adiustably mounted upon the elongated head.

The-aboveobjeots together with others wliich will be -=-apparent'- from ital-redrawing and; followring description, or which maybe' 'later to, may -"-*be-attained*by constructiong theimv proved carbon clamp in the manner-iliustrated in its rear end upon the upper-endofsaid'vertical tive post; with the -improved --carben "clamp projectors.

3 mounted thereon in the position to which it is adjusted when a new carbon is inserted;

Fig. 2 a fragmentary elevation of the improved carbon clamp andthe upper portion of the positive post upon which it is mounted showing the carbon clamping device in the position to which it is later adjusted after the carbon has been partly burned away by use;

Fig. 3 an enlarged transverse section taken as on the line 3-'3, Fig. 2;

Fig.4 a fragmentary bottom plan view of a portion of the head of the improved carbon clamp showing the terminal clamp for the main lead wire;

Fig. 5 a detached perspective view of the head;

Fig. 6 a detached perspective view of theadjustable clamp;

Fig. 7 a fragmentary, longitudinal sectional View of a portion of the interior of a. lamp house showing the positive feed screw with a vertical positive post mounted thereon and the elongated head pivotally connected at its rear end to the vertical post and the carbon clamp upon the elongated head adjusted to the position for receiving a new full length carbon;

Fig. 8 an enlarged detached elevation of the upper ortion of the vertical positive post and the elongated head mounted thereon showing the carbon clamp in the position to which it is adjusted after the carbon has been partially burne away by use; and V i Fig. 9 a detached perspective view of the elongated head shown in Figs. 7 and 8. Referring first to Fig. 1, in which is shown a portion of the interior of a, conventional lamp house such as used in motion picture projectors, the reflector is indicated generally at IEI .and a portion of the negative carbon is shown at H. As in usual practice, this negative carbon is designed to be fed through the central opening [2 in the reflector toward the positive carbon.

V The usual positive feed screw is indicated at :I3 and provided with thegear I4 at one end by means of which it may be operatively connected to a motor for rotating the feed screw to feed the positive carbon toward the negative carbon at a uniform rate of speed as in ordinary practice. i

The usual positive saddle I5 is mounted upon the feed screw I3 and provided with the handle lever I6 by means of which the saddle may be engaged with or disengaged from the screw. The usual positive post I7 is mounted upon thesaddie I5 and provided at its upper end with the spaced ears I8 to which the ordinary carbon clamp is adapted to be connected.

This much of the mechanism is of the same construction as provided in a type of lamp house widely used in connection-with motion picture Owing to the limitations of space within such lamp houses the positive feed screw I 3 can not be more than about ten inches long.

However the carbons provided for such lamp houses are fourteen inches in length and this requires that when a new carbon is inserted into the lamp the carbon cannot be clamped at its end but must be clamped not less than four inches from the end. I r h This clamping of the carbon at a distance from its end frequently results in injury to the carbon at thispoint by cracking or fracturing the same. Owing to the fact that these, carbons have a copper coating upon the exterior this damage-to the interior of the carbon is notusually discovered until the carbon has been burned down The present invention contemplates replacing the ordinary carbon clamp upon the positive post H by an adjustable clamp which includes generally the elongated head I9 and the adjustable parbon clamp 20. Both of these member are formed of suitable conductor metal, the head I9 being'preferably made of cast iron or similar metal and the clamp 29 of steel or the like. The head I9 is provided with a depending ear 2! adaptedto be received between the ears I8 of the positive post and pivotally attached thereto as by the usual screw or bolt 22.

The main lead wire 23 may be connected to the head I9 by means of a terminal comprising the lug 24 formed upon the under side of the head I9 and provided with the serrated half round recess 25 to receivethe wire, a correspondingly shaped cap 26 being connected to the lug as by the screws 21 for clamping the lead wire therebetween. I

The head I9 is provided with a longitudinal guideway comprising the lower flange 28 and upper flange 29 forming a channel in which the .clamping member 20 is slidably mounted. For

the purpose of permitting longitudinal adjustment of the clamping member 23 within this guideway and for clamping it at any adjusted position, an elongated longitudinal slot 30 is formed in the head I9 and a clamping-screw 3i is located through said slot and through a transverse opening 32 in the clamping member 23,

a thumb nut 33 being provided upon the screw for holding-the clamp in adjusted positionupon thehead. r .1 g h In the event that it is necessary to locate the depending ear 2I adjacent to the inner end cf the head I9, as shown in the drawing, a depending counterweight 34 may be formed upon this end of the head to counterbalance the outer end portion of the head located beyond the pivot of the screw 22, so as to hold the positive car bon, indicated at 35, ,in horizontal position so that the free end portion'thereof will feedthrough the usual V-shape guide notch 35 in the post 31 ordinarily provided for that purpose.

" The inner end of the clamp 20 is provided with a longitudinal socket 3 8 of adiameter to receive the endof the carbon 35 and the clamp is slit longitudinallm through said socket as at 39,,the clamping screw. being provided for clamping the end of the. carbon within the end of the socket. v V

The inner end of the clamp is formed V-shaped on its under side as at 4I so that it may be guided throughthe V-shaped guide notch 35 whereby the entire carbon may-be burned with the exception of the small endthereof clamped with the socket 38. V V V 7 Wit this construction it will be obvious that when a new positive carbon is installed in the lamp the end thereof is clamped in the socket 38 of the-clamping member 20 and remains therein untilthe entire carbon has been consumed. When the new carbon is first installed, the clamp 20 is adjusted tothe outer or right hand end of thehead I9 as shown in Fig. 1. After several inches of the carbon has been burned away the clamp 20 may be moved to the inner or left hand end .of: he ea a sh n. n Fie- 2 andclamne provided with the usual gear I4 at its rear end for operatively connecting the screw to a motor as'in usual practice in order to feed the positive carbon toward the negative carbon at a uniform rate of speed.

The positive saddle l5 may be of conventional construction and is oper-atively mounted upon the feed screw and provided with the usual handle lever It by means of which the saddle may be operatively engaged with or disengaged from the said screw.

Instead of providing the usual forwardly inclined positive post as shown in Fig. 1, the positive post ll in this form of the invention is vertical and is mounted upon the saddle H5 in usual manner and provided at its upper end with the spaced ears I8.

As above pointed out with reference to Fig. 1, owing to the length of space within the usual type of lamp house the positive feed screw I3 is limited in length to about ten inches while the carbons which are furnished .for use in such lamp houses are made in fourteen inch lengths.

The elongated head it which is designed for use with the vertical positive post I? is provided at its rear end with the depending ear 2| adapted to be received between the spaced ears I8 of the positive post and pivotally attached thereto as by the usual screw or bolt 22.

A rearwardly extending lug Z4 is formed upon the depending ear 2 l and the clamping cap 26' is connected thereto as by the screws 21 for clamping the lead wire 23 thereto.

The carbon clamp 26' is mounted upon the elongated head l9, between the lower flange 28 and the upper flange 29 thereon which form a guide channel in which the carbon clamp is slidably mounted. The elongated slot 36' is formed in the head I9 between the flanges 28 and 29' and a clamping screw M is located through the carbon clamp 20 and through said slot and provided with a thumb nut 33 for holding the carbon clamp in adjusted position upon the head.

The carbon clamp 2% may be identically the same as carbon clamp 20 shown in Figs. 1 to 6 inclusive and the end of the positive carbon 35 is clamped within the socket 38 of the carbon clamp in the manner above described.

The elongated head 19' extending forwardly from the pivot point 2 i upon the positive post is of suflicient weight to counter balance the weight of the lead wire 23 so as to hold the positive carbon clamp 35 in horizontal position so that the free end portion thereof will feed through the usual V-shape guide notch 36 in the post 31' ordinarily provided for that purpose.

In this :form of the invention as in the form shown in Figs. 1 to 6 and above described, when a new positive carbon is installed the end thereof is clamped in the socket 38' of the carbon clamp 29' and remains there until the entire carbon is consumed. When the new carbon is first inserted the clamp 20 is adjusted to the rear or right handeen nfthegelenea ediheade a e It a v elimi ate tb e $$it pfihandling hot carbons and carbon savers such as are generally used.

Furthermore it should be noted that the improved carbon clamp does not present a surface facing the lamp greater than the ordinary clamp now in use, so that the efficiency of the lamp is not in any way impaired.

I claim:

1. A carbon holder for an arc lamp having a movable post therein and feed means for moving the post, said carbon holder comprising an elongated head, means for detachably connecting said head to the post, a clamping member adjustably mounted upon the head and having a socket for receiving one end of the carbon, and means for clamping the clamping member in adjusted position upon the head at any point throughout the length of the head.

2. A carbon holder for an arc lamp having a movable post therein and feed means for moving the post, said carbon holder comprising an elongated head extending a substantial distance back of the post and having a depending ear, means for detachably connecting said depending ear to the post, there being a longitudinal guideway and a longitudinal slot in the head, a clamping member adjustably mounted in said guideway and having a socket for receiving one end of a carbon, and a clamping screw carried by the clamping member and located through said slot for clamping the clamping member in adjusted position at any point in the guideway.

3. A carbon holder for an arc lamp having a movable post therein and feed means for moving the post, said carbon holder comprising an elongated head, means connecting the rear end of said elongated head to the post, a clamping member adjustably mounted upon the head and having a socket at its forward end for receiving one end of the carbon, and means for clamping the clamping member in adjusted position upon the head at any point throughout the length of the head.

4. A carbon holder for an arc lamp having a movable post therein and feed means for moving the post, said carbon holder comprising an elongated head, means pivotally connecting the rear end of said elongated head to the post, a clamping member adjustably mounted upon the head and having a socket at its forward end for receiving one end of the carbon, and means for clamping the clamping member in adjusted position upon the head at any point throughout the length of the head.

5. A carbon holder for an arc lamp having a movable post therein and feed means for moving the post, said carbon holder comprising an elongated head, nieans for pivotally connecting said head to the post, a clamping member adjustably mounted upon the head and having a socket for receiving one end of the carbon, and means for 'clamping the damping member in adjusted position upon the head at any point throughout the length or the head. I "6. A eajrbon holder for an arc lamp having a movable post therein and feed means for moving the fio s't, said 'o'airbon holder comprising an elongated head; means connecting the rear end of the head to the post, there being a longitudinal guidewayf and a longitudinal slot in the head, a olamp- 7 ing' member adjustably mounted in said guide- 10 Number waly and having a socket at its forward end for reoeiving oneend of the carbon, and a clamping screw carried by the clamping member and locat'ed through said slot for clamping the clamp- The following references are of record in the fileof this patent:

UNITED STATES PATENTS Name Date 554,542 Seaverns Feb. 11, 1896 1,268,548 Deardorfi" June 3, 1918 2,016,065 Wilson Oct. '1', 1935 2,215,401

McCroskey Sept. 17, 1940 

